Wide band flexible section for wave guides



Oct. 31, 1950 H. J. SCHLAFLY, JR

WIDE BAND FLEXIBLE SECTION FOR WAVE GUIDES Filed Feb. 14, 1945 Inventor Hubert J. SchlaF'ly, .111,

His Attorney.

Patented on. 31, 1950 Hubert J; Schla fly, 31"., Cambridge, Mass., assignor to General Electric Company a corpora.-

tion of New York Application February 14, 1945, Serial No. 577,900

' 6 Claims. (01. 178-;44)

My invention relates to dielectric wave guides of the hollow pipe type used for transmission of ultra high frequency energy and, particularly, to a flexible section for use in such guides.

It is known in dielectric wave guide systems used for the propagationof electromagnetic waves that, when adjacent sections of the guide are not axially aligned, reflections of the electromagnetic waves are set up which affect undesirably the transmission of power through the guide. It is desirable, therefore, especially in systems which employ wave guides for transmitting ultra high frequency waves from a transmitter to an oscillating or rotating antenna, to be able to use hollow pipes throughout without resorting to the expedient of converting to either a different mode or type of electromagneticwave for propagation through the hollow pipe or of converting from the Wave guide system to a coaxial or concentric transmission line. system where each plane of freedom or rotation requires a separate set of conversions} Accordingly, it is an object of my inventionto provide a new and improved 1 flexible. section for a wave guide ofthe hollow a new and improved flexible-section for a wave guide of the rectangular hollow-pipe type.

It is a further object .of my invention to provide a new and improved flexible section for a It is a further object of my inventionto provide anew and improved flexible section fora wave guide of the hollow pipe type which is operable over a wide range of ambient tempera.- tures and in which'leakage of ultra high frequency'power is prevented.

It is a still further object of my. invention to provide a new and improved construction tor a flexible section for a wave guide of the hollow pipe type in which all critical dimensions can be accurately established and maintained under all conditionsof flexing. 1

It is a still further object of my invention to provide a new and improved flexible section for a wave guide of the rectangular hollow pipe type which permits hermetic sealing and operation of the section over a wide range of pressures without distortion of the critical dimensions of the wave guide One .of the features of my invention is the forming of a flexible section of a Wave .guide comprising a plurality ofclosely s'pacedmetallic For better understanding of my invention,

reference may be had to the following descripti ntaken in connection with the accompanying e nseed t tor l e ted ou in h @919 laim t e l d s h i ll i l trates an embodiment of the invention as applied to a dielectric wave guide of the rectangular hollow pipe type in which a plurality of half wavechokes is employed; and Fig. 2 is a sectional view of the flexible section of Fig. 1 taken along th lin =Referring to Figs. 1 and 2 jointly, there is win ,a flexible section for dielectric wave g; de of --the rectangular hollow pipe type and through whichelectromagnetic waves, for example o f thetransverse electric type and shown the drawing as TEOl waves, are-propagated. li he ex ible section comprises a plurality of closely spaced transverse substantially rigid metallic disksl each of which is provided with a central- 1y positioned rectangular opening 2 suitable for transmission of transverse electric waves-there,- through. The central rectangular holes of success v disks attes aligned that t tdis 9 the e tit is ali n d with the a d hi one degree of variation. On one of its faces, reach of the disksis provided -with a circular notchpr groove-3 and on its opposite face With a in la s u d an a ort on 101 reduced thiclmesss near the outer edge thereof. A flexible circular snetallic collar member-:Rwhich is positioned between adjacent onesof the disks I and which is: curved, near its outer edge at the point l, has its inner ,edgeB fitting into the shoulder 4 of oneof the adjacent disks and its .outer edge 1 fitting into the natch ,3 ofthe other of the adjacent disks. Preierably,;-the disks l are made oiva goodlconductive material, such as brass. and the collar,ormetallicspinnin .6 is made of a .good conductive material which is likewise exible suchas beryllium copper or phosphor bronze. The]collar; .5 ishermeticallysealed :to adjacent ,ones of the disksat its edges 8 and 9, asiby-zbra ingito theshoulder 4 and by solderin of two adjacent disks I and the collar 6. short circuit is effectively a half wave length from to the notch 3. The flexibility of the spring metal of which the collar 6 is formed permits a substantial angular displacement between adjacent ones of the disks I. When a substantial number of these sections are joined together, as shown in Fig. l, the total angle of bending will be the summation of angles between the individual sections and the resultant flexible section provides a large angular movement for a very short length of the wave guide.

In constructing a flexible section of the type described for use with a wave guide for transmitting an electromagnetic wave of a desired frequency, the mean length of the disk I between points on the notch 3 therein and the mid point I along a leg of the rectangular opening 2 is made equal to an effective half wave length in this radial cavity at this desired operating frequency. The connection of the collar 6 to the disk I in the groove 3 functions as a short-circuit at the end of the radial cavity or transmission line formed between the opposed surfaces This the inner edge I I of the opening in the disk. Ac-

cording to well-known transmission line theory,

the short-circuit at the point of connection of the edge 9 and the collar 6 in the groove 3 of disk I is reproduced across the gap I2 between the surfaces II of two adjacent disks so that substantially zero impedance is encountered across gap I2.

by the mismatch of an adjacent cavity. In this manner, it is possible to reduce the effect of slight mismatching throughout the length of the section and the flexible section as a whole has an improved broad band pass characteristic. It is apparent, of course, that for all waves propagated 'therethrough the wave guide section provides a completely enclosed metallic construction which prevents leakage of any ultra high frequency power, as well as permits hermetic scaling in operation at pressures other than atmospheric pressure without substantial distortion of the flexible walls.

An important advantage of the flexible wave guide construction shown is that all the critical dimensions of the wave guide opening 2, as well as the distances between the walls of this opening and the groove 3, may be accurately machined. The solid construction of the metallic disk I maintains the critical dimensions of the cavity formed between the adjacent disks under all conditions of flexing of the collar member 6. The portion of each disk between the outer edge thereof and the shoulder I3 facilitates flexing of the members 6. It is apparent, moreover, that, while the structure has been shown as applied to a flexible section for a wave guide of the rectangular hollow pipe type, wave guides of any other configuration may be used. Thus, the structure is particularly adapted for use with circular wave guides in which case the dimension 4 of the central opening in the disk member I may be spaced exactly a half wave length away from the short-circuit at the groove 3.

While the invention has been described by reference to a particular embodiment thereof, it will be understood that numerous modifications may be made by those skilled in the art without departing from the invention. I therefore aim in the appended claims to cover all such equivalent variations as come within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letter Patent of the United States is:

l. A flexible section for a wave guide of the rectangular hollow pipe type comprising a plurality of closely spaced metallic disks, each of said disks having substantially planar parallel faces extending outwardly from its axis, the opposed faces of adjacent disks being arranged in substantially parallel relation with a dielectric gap therebetween, flexible metallic members affixed to adjacent ones of said disks, said disks having centrally positioned rectangular apertures through which electromagnetic waves may be propagated, said adjacent ones of said disks and the flexible members affixed thereto forming a section of radial transmission line, and the length of said line being correlated with respect to the frequency of said waves to present a low impedance path for said waves across said gap.

2. A flexible section for a wave guide of the rectangular hollow pipe type comprising a plurality of substantiallyrigid metallic disks having aligned, centrally positioned, rectangular openings therein, flexible, circular metallic members having a central aperture larger than said rectangular opening, said members having inner and outer edges sealed respectively to opposing faces of adjacent ones of said disks to form a sealed enclosure therebetween, the radial distance between said outer edge and the longer leg of said rectangular opening at the mid point thereof being ef fectively equal to a half wave length of the electromagnetic wave propagated through said guide.

3. In a dielectric wave guide system of the I rectangular hollow pipe type, a flexible section therefor comprising a plurality of closely spaced transverse metallic disks having aligned, centrally positioned, rectangular opening therethrough, a flexible metallic collar having a central aperture substantially larger than said openings positioned between adjacent ones of said disks, said collar having inner and outer edges connected respectively to the opposing faces "of said adjacent disks, the radial distance along each of said disks between the edge of the opening therein and the point of connection of the outer edge of the collar associated therewith being of the order of a half wave length at the frequency of the wave propagated through said guide.

4. A flexible section for a wave guide of the hollow pipe type comprising a plurality of closely spaced transverse metallic disks having aligned, centrally positioned, openings therethrough, a flexible metallic collar positioned between adj acent ones of said disks, said collar having inner and outer edges connected respectively to the opposing faces of said adjacent disks, each of said disks being of reduced thickness between the outer edge thereof and the point of connection of said inner edge therewith to permit substantial angular movement between said adiacent disks.

5. A flexible section for a wave guide comprising a pair of spaced rigid metallic disks and an interposed flexible metallic disk having a common axis, said flexible and rigid disks each comprising a pair of'substantially planar parallel faces extending outwardly from said axis, the opposed faces of adjacent disksbeing arranged in substantially parallel relation with a dielectric gap therebetween, said flexible disk having an outer edge connected to one disk of said pair of disks and an inner edge, connected to the other disk of said pair of disks, all of said disks having aligned central apertures of a configuration adapted to transmit an electromagnet Wave supplied thereto.

6. A flexible section for a wave guide comprising a pair of spaced rigid metallic disks and an interposed flexible metallic disk having a common axis, said flexible and rigid disks each comprising a pair of substantially planar parallel faces extending outwardly from said axis, the opposed faces of adjacent disks being arranged in substantially parallel relation with a dielectric gap therebetween, said flexible disk having an outer edge connected to one disk of said pair of disks and an inner edge connected to the other disk of said pair of disks, all of said disks having aligned central apertures, the configuration of said apertures and the distance between said apertures and said outer edge being correlated to the frequency and mode of an electromagnetic wave supplied thereto to effect substantially reflectionless transmission of said wave.

HUBERT J. SCI-ILAFLY, JR.

REFERENCES CITED The following references are of. record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,165,961 Cork July 11, 1939 2,338,441 Kohl Jan. 4, 1944 2,374,498 Quayle Apr. 24, 1945 

